It is known to mount a screen in a frame and mount the latter in a basket mounted within a machine housing adapted to be oscillated or otherwise vibrated as by a cam drive mechanism.
For servicing and replacement it is desirable to be able to remove the screen and its associated frame where provided, from the machine, and to this end the latter is adapted to be slid into and out of the basket and clamping means is provided to hold the frame and screen in position. Clearly it is desirable that the clamping shall be effected as quickly as possible to reduce down time.
It is known to make the frame for the screen inflatable, in order to provide a means for tensioning the screen within the vibratory apparatus. In EP-A-0130744 there is proposed a screen having an inflatable screen frame which on inflation both tensions the screen and clamps it in position in the screening device. However, this arrangement is of limited application. Since the inflation of the screen frame both clamps the screen in position and tensions it, the arrangment cannot be used with screens which are to be tensioned in some other manner such as by a tensioning clip or screw on the basket of the vibratory apparatus or which are pretensioned within a rigid frame. Additionally, since the same act of inflation both clamps the screen and tensions it, the clamping force and the tensioning force cannot be controlled independently. Finally, it is necessary for each screen to be associated with its own respective clamping arrangement, since this is incorporated in the screen frame, even when the screen is not mounted within a vibratory screening apparatus, and thus it is necessary to fabricate as many inflatable frames as there are screens.
It is therefore an object of the present invention to provide an improved clamping mechanism.